Reversible macroscopic dimensional changes (strain) of nanoporous metals such as nanoporous gold or nanoporous platinum can be achieved in an electrochemical environment by controlling the surface stress via the surface electronic charge density which in turn can be controlled by applying an electrical potential.
It would be desirable to achieve macroscopic strain effects in nanoporous metals by using reversible surface-chemistry-driven changes of the surface stress rather than by application of an electrical current in an electrochemical environment. Here, the surface stress of nanoporous metals would be controlled by surface chemistry induced changes of the surface electronic structure rather than by an externally applied potential. This would allow one to directly convert chemical energy into mechanical energy without generating heat or electricity first.